Ok, dit is pas mijn tweede vraag, en het is nogal een doozy. Het is voor een schoolopdracht, maar niemand (inclusief de TA’s) lijkt me te kunnen helpen. Het is nogal een opgave, maar ik weet niet waar ik anders heen moet.
In wezen was de opdracht om een cachesimulator te maken. Deze versie is direct mapping en is eigenlijk maar een klein deel van het hele project, maar als ik dit niet eens onder de knie krijg, heb ik geen kans bij andere verenigingen. Ik post mijn hele code omdat ik geen aannames wil doen over waar het probleem zit.
Dit is de testcase: http://www.mediafire.com/?ty5dnihydnw
En je voert het volgende commando uit:
./sims 512 direct 32 fifo wt pinatrace.out
Je zou moeten krijgen:
hits: 604037
misses 138349
writes: 239269
reads: 138349
Maar ik krijg:
Hits: 587148
Misses: 155222
Writes: 239261
Reads: 155222
Als iemand me op zijn minst in de goede richting zou kunnen wijzen, zou dat zeer op prijs worden gesteld. Ik ben hier ongeveer 12 uur mee bezig geweest.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
struct myCache
{
int valid;
char *tag;
char *block;
};
/*
sim [-h] <cache size> <associativity> <block size> <replace alg> <write policy>
<trace file>
*/
//God willing I come up with a better Hex to Bin convertion that maintains the beginning 0s...
void hex2bin(char input[], char output[])
{
int i;
int a = 0;
int b = 1;
int c = 2;
int d = 3;
int x = 4;
int size;
size = strlen(input);
for (i = 0; i < size; i++)
{
if (input[i] =='0')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='1')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='2')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='3')
{
output[i*x +a] = '0';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
else if (input[i] =='x')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='5')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='6')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='7')
{
output[i*x +a] = '0';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
else if (input[i] =='8')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='9')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='a')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='b')
{
output[i*x +a] = '1';
output[i*x +b] = '0';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
else if (input[i] =='c')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '0';
}
else if (input[i] =='d')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '0';
output[i*x +d] = '1';
}
else if (input[i] =='e')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '0';
}
else if (input[i] =='f')
{
output[i*x +a] = '1';
output[i*x +b] = '1';
output[i*x +c] = '1';
output[i*x +d] = '1';
}
}
output[32] = '\0';
}
int main(int argc, char* argv[])
{
FILE *tracefile;
char readwrite;
int trash;
int cachesize;
int blocksize;
int setnumber;
int blockbytes;
int setbits;
int blockbits;
int tagsize;
int m;
int count = 0;
int count2 = 0;
int count3 = 0;
int i;
int j;
int xindex;
int jindex;
int kindex;
int lindex;
int setadd;
int totalset;
int writeMiss = 0;
int writeHit = 0;
int cacheMiss = 0;
int cacheHit = 0;
int read = 0;
int write = 0;
int size;
int extra;
char bbits[100];
char sbits[100];
char tbits[100];
char output[100];
char input[100];
char origtag[100];
if (argc != 7)
{
if (strcmp(argv[0], "-h"))
{
printf("./sim2 <cache size> <associativity> <block size> <replace alg> <write policy> <trace file>\n");
return 0;
}
else
{
fprintf(stderr, "Error: wrong number of parameters.\n");
return -1;
}
}
tracefile = fopen(argv[6], "r");
if(tracefile == NULL)
{
fprintf(stderr, "Error: File is NULL.\n");
return -1;
}
//Determining size of sbits, bbits, and tag
cachesize = atoi(argv[1]);
blocksize = atoi(argv[3]);
setnumber = (cachesize/blocksize);
printf("setnumber: %d\n", setnumber);
setbits = (round((log(setnumber))/(log(2))));
printf("sbits: %d\n", setbits);
blockbits = log(blocksize)/log(2);
printf("bbits: %d\n", blockbits);
tagsize = 32 - (blockbits + setbits);
printf("t: %d\n", tagsize);
struct myCache newCache[setnumber];
//Allocating Space for Tag Bits, initiating tag and valid to 0s
for(i=0;i<setnumber;i++)
{
newCache[i].tag = (char *)malloc(sizeof(char)*(tagsize+1));
for(j=0;j<tagsize;j++)
{
newCache[i].tag[j] = '0';
}
newCache[i].valid = 0;
}
while(fgetc(tracefile)!='#')
{
setadd = 0;
totalset = 0;
//read in file
fseek(tracefile,-1,SEEK_CUR);
fscanf(tracefile, "%x: %c %s\n", &trash, &readwrite, origtag);
//shift input Hex
size = strlen(origtag);
extra = (10 - size);
for(i=0; i<extra; i++)
input[i] = '0';
for(i=extra, j=0; i<(size-(2-extra)); j++, i++)
input[i]=origtag[j+2];
input[8] = '\0';
// Convert Hex to Binary
hex2bin(input, output);
//Resolving the Address into tbits, sbits, bbits
for (xindex=0, jindex=(32-blockbits); jindex<32; jindex++, xindex++)
{
bbits[xindex] = output[jindex];
}
bbits[xindex]='\0';
for (xindex=0, kindex=(32-(blockbits+setbits)); kindex<32-(blockbits); kindex++, xindex++){
sbits[xindex] = output[kindex];
}
sbits[xindex]='\0';
for (xindex=0, lindex=0; lindex<(32-(blockbits+setbits)); lindex++, xindex++){
tbits[xindex] = output[lindex];
}
tbits[xindex]='\0';
//Convert set bits from char array into ints
for(xindex = 0, kindex = (setbits -1); xindex < setbits; xindex ++, kindex--)
{
if (sbits[xindex] == '1')
setadd = 1;
if (sbits[xindex] == '0')
setadd = 0;
setadd = setadd * pow(2, kindex);
totalset += setadd;
}
//Calculating Hits and Misses
if (newCache[totalset].valid == 0)
{
newCache[totalset].valid = 1;
strcpy(newCache[totalset].tag, tbits);
}
else if (newCache[totalset].valid == 1)
{
if(strcmp(newCache[totalset].tag, tbits) == 0)
{
if (readwrite == 'W')
{
cacheHit++;
write++;
}
if (readwrite == 'R')
cacheHit++;
}
else
{
if (readwrite == 'R')
{
cacheMiss++;
read++;
}
if (readwrite == 'W')
{
cacheMiss++;
read++;
write++;
}
strcpy(newCache[totalset].tag, tbits);
}
}
}
printf("Hits: %d\n", cacheHit);
printf("Misses: %d\n", cacheMiss);
printf("Writes: %d\n", write);
printf("Reads: %d\n", read);
}
Antwoord 1, autoriteit 100%
Je hebt twee problemen. Ten eerste heeft Scott Wales gelijk over je hex2bin()-functie – je hebt een 'x'waar je '4'bedoelt.
Ten tweede, je telt een cache-misser niet correct wanneer je een ongeldig cache-slot raakt. U kunt eenvoudig “ongeldig” afhandelen met exacthetzelfde codepad dat u gebruikt voor een misser:
if ((newCache[totalset].valid == 1) && (strcmp(newCache[totalset].tag, tbits) == 0))
{
/* Hit */
if (readwrite == 'W')
{
cacheHit++;
write++;
}
if (readwrite == 'R')
cacheHit++;
}
else
{
/* Miss (cache entry invalid, or wrong tag) */
if (readwrite == 'R')
{
cacheMiss++;
read++;
}
if (readwrite == 'W')
{
cacheMiss++;
read++;
write++;
}
newCache[totalset].valid = 1;
strcpy(newCache[totalset].tag, tbits);
}